Houkagogakari
Synopsis
The day started out pretty normally. Kei Nimori was just going to elementary school as usual, and although he thought it was weird that his name and some other random person's were written on the chalkboard, he didn't pay too much attention to it—until night fell. Stuck in an alternate dimension of his school, surrounded by horrific monsters and a pile of corpses, his battle for survival has only just begun! The only question is, can he keep fighting until flight becomes an option again...?! (Source: Yen Press)